On Mon, Oct 31, 2011 at 12:58 PM, Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote: > Hi David, > >> We currently have two reference counters for each hci_dev. This patchset tries >> to reduce this to one ref-count and fix several bugs with them. The two >> available ref-counts currently are: >> >> 1) hci_dev->dev internal >> This ref-count is increased by hci_alloc_dev() and decreased inside >> hci_free_dev(). No other code currently uses this refcount. It can be set with >> get_device() and put_device(). >> When this ref-count drops zero, then the hci_dev structure is deallocated (see >> bt_link_release inside hci_sysfs.c), hence, this ref-count is the most important >> one. However, we currently do not use it correctly. >> >> 2) hci_dev->refcnt >> This ref-count is used inside hci_dev_hold/put() and practically used as if it >> would protect the hci_dev structure. However, if this ref-count drops zero, then >> the ->destruct callback is called which is used by all drivers *exclusively* to >> deallocate driver structures and *not* to deallocate or destroy the hci_dev. > > actually I think we should convert the tasklets into one workqueue first > and then integrate deeper into sysfs before trying to hack around this > problem. I am currently playing around with several patches for that but I still need to get away from that single-threaded workqueue as it is quite ugly. > Our core driver registration code is from the 2.4 series and needs major > updating. The sysfs code is glued on top of it and not really well > integrated. So fixing that one properly might make some of these race > conditions go away. Ok. I'll will reconsider sending a new RFC when we fixed the workqueue stuff. As our system is a simple bus-system, it shouldn't be too hard to do that. > Regards > > Marcel Regards David -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
